More for Exam 1 Flashcards
Age of Earth
4.5 billion years old
Hypotheses of how life began
It began on Earth or it began in the extraterrestrial
Things in early atmosphere
CO2, N2, H20, and H2
Plate tectonics
Earth’s crust is broken into enormous plates that are in constant motion, driven by heat rising from the planet’s core. Movement of these plates dramatically shifted the extent and position of the continents over time. There have been major changes in the climates as well.
Pangea
251 MYA;
Supercontinent Pangea assembles, climate warm;
Pangea breaks apart, climate mild/temperate;
North and South America joined by land bridge. Worldwide glaciation.
Gondwana
542 MYA;
Extensive ice on Gondwana. Ocean’s cover much of today’s North America;
Supercontinent of Laurentia to the North and Gondwana to the South. Climate mild
542 MYA
Cambrian explosion
Archaean Eon
First evidence of life
Pre-Cambrian
Hadean, Archaean, and Proterozoic Eons;
Spans from formation of Earth to appearances of most animal groups about 542 MYA;
Almost all life was unicellular and hardly any oxygen was present
Proterozoic
542-2500 MYA;
Eukaryotic cells;
Multicellularity;
some evidence of sexual structure
Phanerozoic eon
542 MYA to present;
We’re technically in it;
Divided into Paleozoic, Mesozoic, and Cenozoic (Us)
Background extinctions
Occurs when normal environmental change, emerging diseases, or competition reduces certain populations to zero
Mass extinction
Result from extraordinary, sudden, and temporary changes in the environment
End-Permian Extinction
Most species wiped out on Earth
End-Cretaceous
Wiped out dinosaurs
Genera
Basic units of classification
Binomials
Two-part names
Ex. Homo Sapiens
Taxonomy
The science of classifying living things
Taxon
A classification level
Endosymbiosis
Mitochondria and chloroplasts most likely gain entry through this
Eukarya
may really be the result of combination of cells from each of the other two major domains, Archaea and Bacteria.
Mammalian Family Tree
Continues to emerge based on molecular data;
The majority of mammals are either eutherians or placental mammals;
Now divided into 4 major groups;
First major split was 100 MYA, when Africa split from South America;
Paleozoic Era
Covers the interval from 542 to 251 MYA;
Many animal groups appeared here;
Ends with obliteration of almost all multicellular life-forms at the end of Permian period
Mesozoic Era
Age of reptiles;
Covers intervals from 251 to 65.5 MYA;
Saw the rise and dominance of the dinosaurs and ended with their extinction
